The proposed research projects are directed toward 1) the metabolic behaviour of the mammalian (rat) lung and 2) the role of potassium and bicarbonate in modifying the responsiveness of the respiratory control system in man. The mammalian lung is uniquely capable of synthesizing the lipid components of surfactant, the substance which coats the alveoli to stabilize surface tension of the lung at varying volumes. During the past year the effect of alcohol on the rate of phospholipid turnover has been measured. It was found that the ingestion of alcohol limits the incorporation of palmitate into phospholipids. In the coming year the studies will be expanded to establish whether a specific step in phosphatidylcholine synthesis is inhibited by alcohol ingestion. In addition studies will be initiated to assess the role of anaerobic metabolic pathways in the formation of phospholipids at low oxygen tensions and following inhibition of the oxidative pathway of metabolism. Studies to assess the role of potassium in modifying the responsiveness of the respiratory control mechanism in man are to be continued. The available observations seem to indicate that extracellular bicarbonate concentration rather than potassium depletion is the major determinant in modifying the responsiveness to CO2 inhalation in hypokalemic alkalosis. Further studies are in progress to establish how resting ventilation and the response to CO2 inhalation is modified by this electrolyte imbalance.